Anterior-posterior Projection Research Articles

Establishment of Diagnostic Reference Levels for Radiography in 10-year-old Pediatric Patients in Republic of Korea

The diagnostic reference levels (DRLs) for a 10-year-old patient were established for the most common types of general radiography in this study, using a glass dosimeter and a phantom corresponding to the international standards. The DRLs are set by measuring the entrance surface doses (ESD) at 211 medical institutions. The ESD of the skull posterior-anterior (PA) projection is between 0.11 and 5.59 mGy, with the average dose at 1.03 mGy, and the third quartile value at 1.17 mGy. The ESD of the skull lateral (LAT) projection is between 0.08 and 5.20 mGy, with the average dose at 0.78 mGy, and the third quartile value at 0.96 mGy. The ESD of the chest PA projection is between 0.01 and 1.38 mGy, with the average dose at 0.18 mGy, and the third quartile value at 0.20 mGy. The ESD of the chest LAT projection is between 0.04 and 3.36 mGy, with the average dose at 0.42 mGy, and the third quartile value at 0.46 mGy. The ESD of the abdomen AP projection is between 0.09 and 4.64 mGy, with the average dose at 0.85 mGy, and the third quartile value at 1.13 mGy. The ESD of the pelvis AP projection is between 0.1 and 5.26 mGy, with the average dose at 0.85 mGy, and the third quartile value at 1.06 mGy. Based on third quartile values and through clinical expert consultation, the DRLs for 10-year-olds in Korea were established at 1.1 mGy for skull PA, 0.9 mGy for skull LAT, 0.2 mGy for chest PA, 0.4 mGy for chest LAT, 1.1 mGy for abdomen AP, and 1.0 mGy for pelvis AP.

REPORT OF DENTAL ALTERATIONS IN AN ARNOLD-CHIARI TYPE 2 SYNDROME PATIENT

Arnold-Chiari syndrome is characterized by enlargement of the cerebellar tonsils going through the foramen magnum, reaching the spinal canal. The syndrome has 4 ratings: type I (asymptomatic in childhood), types II and III (diagnosed in the second week life), and type IV (incompatible with life). Oral alterations are rarely described, tooth agenesis being the most common. This study aims to report the case of a 3-year-old patient who is an Arnold-Chiari syndrome type II carrier with dental alterations. The case was evaluated by the hospital dentistry team because of the dental changes. Based on clinical finds, a skull x-ray (posterior-anterior projection, oblique lateral x-ray) where dental anomaly of number (supranumerary teeth) and enamel hypoplasia was observed. Topic fluor applications and monitoring are being made. The consistent clinical presentation provides further evidence of the dental characteristics of Arnold-Chiari type II syndrome patients. Arnold-Chiari syndrome is characterized by enlargement of the cerebellar tonsils going through the foramen magnum, reaching the spinal canal. The syndrome has 4 ratings: type I (asymptomatic in childhood), types II and III (diagnosed in the second week life), and type IV (incompatible with life). Oral alterations are rarely described, tooth agenesis being the most common. This study aims to report the case of a 3-year-old patient who is an Arnold-Chiari syndrome type II carrier with dental alterations. The case was evaluated by the hospital dentistry team because of the dental changes. Based on clinical finds, a skull x-ray (posterior-anterior projection, oblique lateral x-ray) where dental anomaly of number (supranumerary teeth) and enamel hypoplasia was observed. Topic fluor applications and monitoring are being made. The consistent clinical presentation provides further evidence of the dental characteristics of Arnold-Chiari type II syndrome patients.

Technical Note: Assessment of scatter originating from the x-ray tube collimator assembly of modern angiography systems.

While scatter from the patient is assumed to be the primary source of occupational radiation dose associated with fluoroscopically guided interventional procedures, the potential contribution of scatter from the x-ray collimator assembly is unknown. The purpose of this work was to survey clinical x-ray angiography systems to assess the potential contribution of collimator assembly scatter on occupational radiation dose. Experimental methods were designed to measure the relative contributions of scatter originating from within the collimator assembly of the x-ray tube to total scatter, which included scatter from a patient-simulating phantom. Measurements were acquired as a function of lateral distance from the x-ray beam center using a posterior anterior (PA) projection and at a fixed location for variable right anterior oblique to left anterior oblique projections in the range -90º to 90º. For one system, the collimator assembly was partially disassembled to assess the scatter contribution of individual components. For two systems, 0.5mm Pb was added to the inner surface of the collimator assembly cover and tested for efficacy to block collimator assembly scatter. Considering all x-ray systems and only the PA projection, collimator assembly scatter contributed 20-50% to total scatter. For x-ray projection angles of -90º to 90º, the relative contribution of collimator assembly to total scatter was dependent on projection angle and ranged from 5% to 56%. X-ray systems with kerma-area product meters demonstrated higher collimator assembly scatter than those without. Considering all projection angles, the addition of 0.5mm Pb to the inside of the collimator assembly cover reduced collimator assembly scatter from 28% to 16% of total scatter for both systems. Findings from this work suggest that contemporary radiation safety practices and guidelines should be revised to account for scatter originating from the collimator assembly of angiographic x-ray tubes.

Effects of denosumab on hypercalcemia and bone mineral density loss in kidney transplant recipients .

Hypercalcemia and bone mineral density (BMD) loss are serious problems associated with post-transplant chronic kidney disease-mineral and bone disorder. The present study aimed to clarify the effects of denosumab on hypercalcemia complicated with BMD loss in kidney transplant recipients. Among 100 consecutive adult kidney transplant recipients, 16 patients with serum corrected Ca (cCa) levels ≥11.0mg/dL were included in a severe hypercalcemia group. In 14 patients (excluding 2 patients who underwent parathyroidectomy) with severe hypercalcemia and low BMD at the lumbar spine (T-score < -1.0), 60mg of denosumab were administered by subcutaneous injection at 6-month intervals. Serum cCa and alkaline phosphatase (ALP) levels were analyzed before and after denosumab administration. Lumbar spinal BMD was compared between, before, and 12months after denosumab administration. Both serum cCa (11.7mg/dL) and ALP (525U/L) levels declined promptly after denosumab administration, with only the cCa level showing rebound. Additionally, serum cCa and ALP levels were significantly lower after denosumab administration (all time points) than before denosumab administration. Lumbar spinal BMD increased significantly 12 months after denosumab administration when compared with the value before denosumab administration in both anterior-posterior (increase rate: 5.0%) and lateral (increase rate: 5.4%) projections. Denosumab could improve hypercalcemia and BMD loss in kidney transplant recipients. Therapeutic intervention involving denosumab should be considered for hypercalcemia and BMD loss associated with post-transplant chronic kidney disease-mineral and bone disorder.

Quantifying dose-creep for Skull and chest radiography using dose area product and entrance surface dose: Phantom study

Digital radiography allows for image manipulation, giving radiographers the ability to adjust the grey level of the image using latitude-algorithm. In doing such, patients receiving unnecessary radiation-dose often goes undetected. The aim of present study has been to quantify dose-creep using dose area product (DAP) and entrance surface dose (ESD) for skull and chest exams using phantoms. Furthermore, to investigate possible correlation between DAP and ESD. Adult anthropomorphic phantoms were used to produce a series of anterior-posterior (AP) and lateral (LAT) skull and chest images varying the mAs to yield optimal and overexposed images for each projection. Thermoluminescent dosimeter (TLD) was placed at the surface of the centered phantom to measure the ESD. DAP values were gathered and correlated with ESD values using Spearman's correlation coefficient test while Wilcoxon-test was used to calculate the statistical difference. Dose-creep was calculated as the percentage difference between optimum and over exposure results. The highest estimated dose-creep of (51%) was demonstrated for chest AP projection as calculated from DAP values. Using Spearman's correlation, a significant strong positive correlation was revealed for DAP and ESD optimum (r = 0.916, p = 0.0006) and overexposure (r = 0.8992, p = 0.0009), respectively. Dose-creep can be considerably high raising the need for thorough investigations and society awareness.

Evaluation of the dose reduction capabilities in digital radiography of the chest using contrast-detail phantom

Assessment of the quality of the images obtained using optimized (low-dose) protocols is the inherent part of the optimization in X-ray diagnostics. To perform the objective quantitative image quality assessment one can use dedicated test-objects, including several components for the simultaneous measurement of the different physical image characteristics (contrast and spatial resolution). The use of such test objects allows estimating and assessing the relations between the patient dose, parameter of the X-ray examination and image quality. That is especially important for the optimization of the digital radiographic examinations performed with automated exposure control. The aim of the current study was to evaluate the possibilities of the patient dose reduction using “contrast-detail” test-object for the digital radiography of the chest in posterior-anterior projection performed with automated exposure control. The study was performed in St-Petersburg Mariinsky hospital on a digital X-ray unit “ARC-Electron” with a flat-panel detector. The combination of a test-object and a tissue-equivalent phantom were imaged on a range of chest X-ray protocols: on a 60–150 kV tube voltage range with automated exposure control; and using fixed 90 kV tube voltage on a range of 2–100 mAs tube current-exposure time product. Dose-area product (cGy×cm2) was measured for each exposure; effective dose (mSv) was estimated for each exposure based on dose-area product. A dedicated software was developed for the automated image quality assessment. The results of the study indicate that the use of a high tube voltage (140–150 kV) with current automated exposure control settings would lead to 60% and 95% reduction of the dose-area product and effective dose, respectively, compared to the standard protocol. The adjustment of the current automated exposure control settings with the reduction of the tube current-exposure time product from 11,2 mAs to the 4,2 mAs for the tube voltage of 90 kV would lead to the reduction of both the dose-area product and effective dose up to a factor of three, compared to the standard protocol. For both scenarios image quality characteristics decreased by less than 15%. The proposed low-dose protocols are under the clinical approbation at Mariinsky hospital. The proposed method of image quality assessment and development of low-dose protocols is recommended for inclusion in the quality assurance program for the radiography examinations.

Subregional areal bone mineral density (aBMD) is a better predictor of heterogeneity in trabecular microstructure of vertebrae in young and aged women than subregional trabecular bone score (TBS)

Currently, bone densitometry fails to identify nearly half of those elderly patients at immediate fracture risk. To improve clinical assessment of vertebral fracture risk, we aimed to determine how the DXA-based 2D parameter Trabecular Bone Score (TBS) relates to subregional variability in 3D trabecular microstructure in young and elderly women compared to aBMD. T12 vertebrae from 29 women (11 young: 32 ± 6 years, 18 aged: 71 ± 5 years) were DXA-scanned ex vivo in anterior-posterior (AP) and lateral projection providing vertebral aBMD and TBS. Additionally, aBMD and TBS were measured for three horizontal (superior, mid-horizontal, inferior) and three vertical subregions (anterior, mid-vertical, posterior) and related to 3D microstructure indices, i.e. bone volume per tissue volume (BV/TV), trabecular number and thickness (Tb.N, Tb.Th), based on HRpQCT. Subregional high-resolution tomography showed significant differences in trabecular parameters for both age groups: In horizontal subregions, BV/TV was lowest superiorly, Tb.Th was highest mid-horizontally, and Tb.N was lowest mid-horizontally and highest inferiorly. Correspondingly, aBMD varied between horizontal subregions, with differences depending on projection direction. TBS varied only in lateral projections of the aged group, with lower values for the mid-horizontal subregion. In vertical subregions, BV/TV, Tb.N, and aBMD were highest posteriorly for both groups. TBS did not differ between vertical subregions. Regression analysis showed aBMD as a predictor explained more of the variance in subregional 3D microstructure compared to TBS. Stepwise multi-regression analysis revealed only three combinations of subregion, projection, and group where aBMD and TBS were both significant predictors. Subregional aBMD reflects variations in trabecular bone microstructure better than subregional TBS for trisected regions. Specifically, lateral aBMD identifies microstructural heterogeneities independent of age and may improve prediction of vertebral strength and susceptibility to specific fracture types.

Low inter-observer agreement among experienced shoulder surgeons assessing overstuffing of glenohumeral resurfacing hemiarthroplasty based on plain radiographs

BackgroundIn a clinical setting, a visual evaluation of post-implant radiographs is often used to assess the restoration of glenohumeral joint anatomy after resurfacing hemiarthroplasty and is a part of the decision-making process, in combination with other parameters, when evaluating patients with inferior clinical results. However, the reliability of this method of visual evaluation has not been reported. The aim of this study was to investigate the inter- and intra-observer agreement among experienced shoulder surgeons assessing overstuffing, implant positioning, and size following resurfacing hemiarthroplasty using plain standardized radiographs.MethodsSix experienced shoulder surgeons independently classified implant inclination, size of the implant and if the joint seemed overstuffed, in 219 cases of post-implant radiographs. All cases were classified twice 3 weeks apart. Only radiographs with an anterior-posterior projection with a freely visible joint space were used. Non-weighted Cohen’s kappa values were calculated for each coder pair and the mean used as an estimate of the overall inter-observer agreement.ResultsThe overall inter-observer agreement for implant size (kappa, 0.48 and 0.41) and inclination angle was moderate in both rounds (kappa, 0.46 and 0.44), but only a fair agreement was found concerning the evaluation for stuffing of the joint (kappa, 0.24 and 0.28). Intra-observer agreement for implant size and stuffing ranged from fair to substantial while the agreement for inclination was moderate to substantial.ConclusionsOur results indicate that a visual evaluation of plain radiographs may be inadequate to evaluate overstuffing, implant positioning, and size following resurfacing hemiarthroplasty using plain standardized radiographs. Future studies may contribute to elucidate whether reliability increases if consensus on clear definitions and standardized methods of evaluation is made.

Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections.

The goal of the study was to determine the potential impact of system inaccuracies and table attenuation on fluoroscope-reported dose values. An Institutional Review Board-approved study was conducted to collect detailed acquisition and patient exposure data for fluoroscopy-guided lumbar epidural injections. System-reported dosimetry values, especially the air Kinetic Energy Released per unit MAss and dose-area product metrics, are routinely used for estimating the radiation burden to patients undergoing fluoroscopy-guided procedures. However, these metrics do not account for other factors, such as acquisition geometry, where the table may attenuate a substantial fraction of the x-ray intensity, and system dosimetry inaccuracies, which are only required to be accurate within ±35%. Acquisition data from 46 patients undergoing fluoroscopy-guided lumbar epidural injections were collected to better estimate the true incident dose-area product. Gantry angles, x-ray technique factors, and field sizes were collected to characterize each procedure. Additionally, the fluoroscope dosimetry accuracy and table attenuation properties were evaluated as a function of kVp to generate the correction factors necessary for accurate dosimetry estimates. The system-reported values overestimated the total patient entrance dose-area product by an average of 34% (13-44%). Errors may be substantially higher for systems with less accurate fluoroscopes or more anterior-posterior projections. Correcting system-reported dosimetry values for systematic inaccuracies and variability can substantially improve fluoroscopic dose values. Including corrections for system output inaccuracies and acquisition factors such as table attenuation is necessary for any reliable assessment of radiation burden to patients associated with fluoroscopy-guided procedures.

Imaging Pitfalls of the Acutely Traumatized Pediatric Elbow.

A four-year-old otherwise healthy girl presented to our outpatient clinic complaining of left elbow pain and swelling. The child’s parents reported an indoor trauma the previous day. On clinical examination, the left elbow and forearm exhibited diffuse swelling. The gentle passive range of elbow and forearm motion was normal and mostly pain-free. Nevertheless, the radial head was stable but a palpable click was noted. The neurovascular examination was normal. The patient received radiographs of the traumatized left and normal right elbow [Figures 1 and ​and2].2]. Radiographs of her left forearm were unremarkable. Open in a separate window Figure 1 Left elbow radiographs. (a) Two anterior-posterior projections of the left elbow. Note the presence of a well-ossified medial epicondyle epiphysis (red arrow) and simultaneous absence of the radial head epiphysis. Typically, the center of the radial head should ossify before that of the medial epicondyle. Notice the notched radial metaphysis (blue arrow). This notching is undetected in the other projection because of forearm rotation as indicated by radioulnar overlap. (b) Lateral view verifies the presence of well-ossified medial epicondyle epiphysis (red arrow) and simultaneous absence of the radial head epiphysis.

Estimating Thyroid Doses From Modified Barium Swallow Studies.

This study sought to obtain factors to convert entrance air kerma into thyroid doses for patients undergoing modified barium swallow studies. A commercial software package (PCXMC 2.0.1) was used to calculate patient thyroid doses from modified barium swallow studies, which were divided by the entrance air kerma to yield fthyroid ratios. Exposure in the lateral and posterior-anterior projections were considered where the thyroid was directly irradiated. Calculations were obtained for adult patients as well as children ranging from birth to 10 y old. The average value of fthyroid in a normal-sized adult was 0.63 ± 0.11 in the lateral projection and 0.18 ± 0.06 for an upper gastrointestinal posterior-anterior projection. Increasing the beam quality from the lowest (60 kV + 3 mm aluminum) to the highest (110 kV + 3 mm aluminum + 0.2 mm copper) values investigated nearly doubled the value of fthyroid from 0.42 to 0.79 in the lateral projection and quadrupled the value from 0.07 to 0.29 in the upper gastrointestinal posterior-anterior projection. Values of fthyroid decreased with increasing body mass index. Average values of fthyroid in 10 y olds were similar to those of adults but always increased as the age of the exposed child was reduced. The average fthyroid for newborns was 0.84, nearly one-third higher than the corresponding ratio for normal-sized adults.

P052] Influence of X-ray field position on doses in organs and tissues for chest radiography

Purpose We studied how changing of the field position influences the absorbed doses in organs and tissues during chest radiography. Methods The ICRP voxel phantoms were adopted for modelling of chest radiography in posterior-anterior projection. The parts of phantoms that lie inside the beam and scattered radiation region located at the distance of 15 cm from the field edge were taken. The TASMIP model was used for the spectrum of X-ray tube. The following parameters were taken into account: anode voltage, filtration, voltage ripple, the focus-to-detector distance and the field size. Monte-Carlo simulation of X-ray transport within the chosen parts of phantoms was used [1] . At the standard position the center of X-ray field lied 40 cm from the top of the male phantom and 36.8 cm from the top of the female phantom. 5% to 20% shifts of the field center were considered. Results Changes in X-ray field position cause large differences in organ doses for organs that originally lied inside the beam or on the boundaries of the beam volume. After the field center shift by 20% up from the standard position the absorbed dose in adrenals of male decreases by a factor of 8.6. This effect is less than 20% for large organs and tissues such as lungs, muscle or skin. After the field center shift by 20% down the standard position the absorbed dose in female lungs decreases by 6%. Doses to organs of female are almost always larger than doses to the same organs of male. For standard field position the doses in female’s liver and lungs are 1.6 and 1.8 times higher than corresponding doses for male phantom. Conclusions Shift of X-ray field position up and down from the standard value should be considered for dose optimization during chest radiography. Differences between male and female bodies should be taken into account for more accurate patient dose assessment.

Characterization of a novel liquid fiducial marker for multimodal image guidance in stereotactic body radiotherapy of prostate cancer.

Liquid fiducial markers have shown to be a promising alternative to solid gold markers in terms of imaging artifact reduction, patient comfort, and compatibility with different imaging modalities. This study aims to investigate the performance of the novel BioXmark® liquid marker for state-of-the-art multimodal imaging used in prostate cancer (PCa) radiotherapy, encompassing kV CT/CBCT, multiparametric MRI, and kV x-ray imaging. In addition, automatic detection of the liquid markers in x-ray imaging for prostate motion monitoring during treatment was investigated. A total of eight BioXmark® liquid markers with varying volumes (range 5-300 μL) were casted on a square grid into a gelatin phantom insert. A cylindrical gold marker (QLRAD, length = 7 mm, Ø = 1 mm) was inserted for reference. Liquid marker visibility and streaking artifacts in CT/CBCT imaging were evaluated by placing the gelatin phantom into a CIRS anthropomorphic phantom. Relevant MRI characteristics such as the T2 and T1 relaxation times, the ADC value, and the relative proton density (ρH) were quantified by placing the gelatin phantom insert next to a T1MES mapping phantom and a water-filled syringe for reference. Ex vivo multiparametric MRI images were acquired by placing the gelatin phantom next to a resected prostate specimen. Anterior-posterior x-ray projection images were obtained by placing the gelatin phantom insert on top of an anthropomorphic pelvic phantom with internal pelvic bony structures and were acquired for five positions relative to the bony anatomy and 24 clinically relevant x-ray exposure settings. To quantify individual automatic marker detection, single markers were artificially isolated in the x-ray images using postprocessing. Markers of all sizes were clearly visible on CT and CBCT images with only the largest marker volumes (100-300 μL) displaying artifacts similar in size to the gold fiducial marker. Artifact size increased with increasing liquid marker volume. Liquid markers displayed good contrast in ex vivo T1-weighted and ρH-weighted images. The markers were not visible in the ex vivo T2-weighted image. The liquid markers induced a chemical shift artifact in the obtained ADC-map. Automated detection in x-ray imaging was feasible with high detection success (four of five positions) for marker volumes in the range of 25-200 μL. None of the liquid markers were detected successfully when superimposed on a bony edge, independent of their size. This study is the first to show the compatibility of BioXmark® liquid markers with multimodal image-guided radiotherapy for PCa. Compared to a solid gold marker, they had favorable results in both visibility and induced imaging artifacts. Liquid marker visibility in MRI imaging of the prostate does not solely depend on the low ρH value (not visible on T2-weighted image) but is also influenced by its relaxation times. Automated marker detection in x-ray images was feasible but better adapted marker detection algorithms are necessary for marker localization in the presence of bony edges. Hence, the liquid marker provides a minimally invasive (fine needles) and highly applicable alternative to current solid gold markers for multimodal image-guided prostate radiotherapy treatments.

Model evaluation of rapid 4-dimensional lung tomosynthesis

PurposeThis is an investigation of a lung motion digital tomosynthesis (DTS) model using combined stationary detector and stationary cold cathode x-ray sources at projection acquisition rates that exceed the present norms. The intent is to reduce anatomical uncertainties from artifacts inherent in thoracic 4-dimensional computed tomography (CT). Methods and materialsParameters necessary to perform rapid lung 4-dimensional DTS were studied using a conventional radiographic system with linear motion of the x-ray source and a simple hypothetical hardware performance model. Hypothetical rapid imaging parameters of sweep duration, projections per second, pulse duration, and tube current (mA) were derived on the basis of 0.5 mm and 1 mm motion captures per phase, 10 and 15 breaths per minute (bpm), 10 to 40 mm breathing amplitude, and 2 signal-to-noise ratio (SNR) levels. Anterior-posterior and lateral projection images of a normal size anthropomorphic thorax phantom with iodine contrast inserts were collected and reconstructed with an algebraic algorithm to study the effects of reduced x-ray output associated with field emission cold cathodes composed of carbon nanotubes or metal Spindt-type. Radiographic projections were collected at 3 SNR levels that were set at standard clinical DTS milliampere-seconds (mAs) and reduced corresponding to 50% and 25% standard DTS mAs to simulate a reduced x-ray output. ResultsThe DTS SNR of the inserts was superior in all reconstructions at clinical mAs versus automatic exposure-control radiographs and superior in 3 of 4 at the 50% and 25% mAs levels. The most demanding performance parameters corresponding to 40 mm amplitude, 15 bpm, 0.5 mm motion capture limit, and 61 projections were sweep duration (10.4 msec), projection rate (5862 projections per second), pulse duration (0.161 msec), current 189 mA anterior-posterior, and 653 mA lateral. ConclusionsFeasibility depends on the output performance of stationary cold cathode hardware being developed for DTS. Present image receptor technology can accommodate frame acquisition rates.

Plan in 2-D, execute in 3-D: an augmented reality solution for cup placement in total hip arthroplasty.

Reproducibly achieving proper implant alignment is a critical step in total hip arthroplasty procedures that has been shown to substantially affect patient outcome. In current practice, correct alignment of the acetabular cup is verified in C-arm x-ray images that are acquired in an anterior-posterior (AP) view. Favorable surgical outcome is, therefore, heavily dependent on the surgeon's experience in understanding the 3-D orientation of a hemispheric implant from 2-D AP projection images. This work proposes an easy to use intraoperative component planning system based on two C-arm x-ray images that are combined with 3-D augmented reality (AR) visualization that simplifies impactor and cup placement according to the planning by providing a real-time RGBD data overlay. We evaluate the feasibility of our system in a user study comprising four orthopedic surgeons at the Johns Hopkins Hospital and report errors in translation, anteversion, and abduction as low as 1.98mm, 1.10deg, and 0.53deg, respectively. The promising performance of this AR solution shows that deploying this system could eliminate the need for excessive radiation, simplify the intervention, and enable reproducibly accurate placement of acetabular implants.

Propose for the Benchmark Dose (BD) for the Optimization of Protection in Medical Exposure in General Radiography

The goal of this research was to create the most appropriate index dose for the optimization of protection in medical exposure in general radiography in Kanagawa prefecture. We distributed questionnaires to 272 medical institutions in Kanagawa prefecture. The investigation period was from October 2015 to February 2016. Entrance surface dose (ESD) was used as the index dose. Investigated regions in general radiography were the adult chest, adult abdomen, and infant chest (anterior-posterior projections for all regions). The effective response rate was 35%. ESD was significantly lower with a flat panel detector (FPD) than with computed radiography (CR) in all regions (adult chest and abdomen: p<0.001; infant chest: p<0.05) [e.g., mean (±standard deviation) ESD in the adult chest was 0.16±0.06 mGy with FPD and 0.24±0.10 mGy with CR]. In the infant chest with CR, ESD was significantly higher using a grid (0.15±0.07 mGy) compared to not using a grid (0.10±0.05 mGy; p<0.05). Based on these results, we propose the benchmark dose of each medical equipment, such as adult chest: FPD, 0.2 mGy; CR, 0.3 mGy.

Which measuring site in ankylosing spondylitis is best to detect bone loss and what predicts the decline: results from a 5-year prospective study

BackgroundStudies have shown increased prevalence of osteoporosis and increased risk for vertebral fractures in patients with ankylosing spondylitis (AS). Measurements of bone mineral density (BMD) in the lumbar spine anterior-posterior (AP) projection may be difficult to interpret due to the ligamentous calcifications, and the lateral projection might be a better measuring site. Our objectives were to investigate BMD changes after 5 years at different measuring sites in patients with AS and to evaluate disease-related variables and medications as predictors for BMD changes.MethodsIn a longitudinal study, BMD in Swedish AS patients, 50 ± 13 years old, was measured with dual-energy x-ray absorptiometry (DXA) at the hip, the lumbar spine AP and lateral projections, and the total radius at baseline and after 5 years. Patients were assessed with questionnaires, blood samples, and spinal radiographs for grading of AS-related alterations in the spine with the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and assessment of vertebral fractures by the Genant score. Multiple linear regression analyses were used to investigate predictors for BMD changes.ResultsOf 204 patients included at baseline, 168 (82%) were re-examined after 5 years (92 men and 76 women). BMD decreased significantly at the femoral neck and radius and increased significantly at the lumbar spine, both for AP and lateral projections. Mean C-reactive protein during follow-up predicted a decrease in the femoral neck BMD (change in %, β = –0.15, p = 0.046). Use of bisphosphonates predicted an increase in BMD at all measuring sites (p < 0.001 to 0.013), except for the total radius. Use of tumor necrosis factor inhibitors (TNFi) predicted an increase in AP spinal BMD (β = 3.15, p = 0.012).ConclusionThe current study (which has a long follow-up, many measuring sites, and is the first to longitudinally assess the lateral projection of the spine in AS patients) surprisingly showed that lateral projection spinal BMD increased. This study suggests that the best site to assess bone loss in AS patients is the femoral neck and that inflammation has an adverse effect, and the use of bisphosphonates and TNFi has a positive effect, on BMD in AS patients.

Correlation Between Contrast Time-Density Time on Digital Subtraction Angiography and Flow: An inVitro Study.

Digital subtraction angiography (DSA) provides an excellent anatomic characterization of cerebral vasculature, but hemodynamic assessment is often qualitative and subjective. Various clinical algorithms have been produced to semiquantify flow from the data obtained from DSA, but few have tested them against reliable flow values. An arched flow model was created and injected with contrast material. Seventeen injections were acquired in anterior-posterior and lateral DSA projections, and 4 injections were acquired in oblique projection. Image intensity change over the angiogram cycle of each DSA run was analyzed through a custom MATLAB code. Time-density plots obtained were divided into 3 components (time-density times, TDTs): TDT10%-100% (time needed for contrast material to change image intensity from 10% to 100%), TDT100%-10% (time needed for contrast material to change image intensity from 100% to 10%), and TDT25%-25% (time needed for contrast material to change from 25% image intensity to 25%). Time-density index (TDI) was defined as model cross-sectional area to TDT ratio, and it was measured against different flow rates. TDI10%-100%, TDI100%-10%, and TDI25%-25% all correlated significantly with flow (P < 0.001). TDI10%-100%, TDI100%-10%, and TDI25%-25% showed, respectively, a correlation coefficient of 0.91, 0.91, and 0.97 in the anterior-posterior DSA projections (P < 0.001). In the lateral DSAprojection, TDI100%-10% showed a weaker correlation (r= 0.57; P= 0.03). Also in the oblique DSA projection, TDIs correlated significantly with flow. TDI on DSA correlates significantly with flow. Although invitro studies might overlook conditions that occur in patients, this method appears to correlate with the flow and could offer a semiquantitative method to evaluate the cerebral blood flow.

PATIENT RADIATION DOSE FROM CHEST X-RAY EXAMINATIONS IN THE WEST BANK—PALESTINE

Radiation doses to patients resulting from chest X-ray examinations were evaluated in four medical centers in the West Bank and East Jerusalem-Palestine. Absorbed organ and effective doses were calculated for a total of 428 adult male and female patients by using commercially available Monte Carlo based softwares; CALDOSE-X5 and PCXMC-2.0, and hermaphrodite mathematical adult phantoms. Patients were selected randomly from medical records in the time period from November 2014 to February 2015. A database of surveyed patients and exposure factors has been established and includes: patient's height, weight, age, gender, X-ray tube voltage, electric current (mAs), examination projection (anterior posterior (AP), posterior anterior (PA), lateral), X-ray tube filtration thickness in each X-ray equipment, anode angle, focus to skin distance and X-ray beam size. The average absorbed doses in the whole body from different projections were: 0.06, 0.07 and 0.11 mGy from AP, PA and lateral projections, respectively. The average effective dose for all surveyed patients was 0.14 mSv for all chest X-ray examinations and projections in the four investigated medical centers. The effect of projection geometry was also investigated. The average effective doses for AP, PA and lateral projections were 0.14, 0.07 and 0.22 mSv, respectively. The collective effective dose estimated for the exposed population was ~60 man-mSv.

EFFECTIVE DOSE PER UNIT KERMA-AREA PRODUCT CONVERSION FACTORS IN ADULTS UNDERGOING MODIFIED BARIUM SWALLOW STUDIES.

This study presents an investigation of adult effective dose (E) per unit Kerma-Area Product (KAP) in Modified Barium Swallow Study (MBSS) examinations. PC program for X-ray Monte Carlo (version 2.0.1) was used to calculate patient organ doses during MBSS examinations, which used combined to generate effective dose. Normalized patient doses were obtained by dividing the effective dose (mSv) by the incident KAP (Gy·cm2). Five standard projections were studied and the importance of X-ray beam size and in patient size (body mass index) were investigated. Lateral projections had an average E/KAP conversion factor of 0.19 ± 0.04 mSv/Gy·cm2. The average E/KAP was highest for upper gastrointestinal (GI) anterior-posterior projections (0.27 ± 0.04 mSv/Gy·cm2) and lowest for upper GI posterior-anterior projections (0.09 ± 0.03 mSv/Gy·cm2). E/KAP always increased with increasing filtration and/or X-ray tube voltage. Reducing the X-ray beam cross-sectional area increased the E/KAP conversion factors. Small patients have the E/KAP conversion factors that are twice those of a standard adult. Conversion factors for effective dose of adult patients undergoing MBSS examinations must account for X-ray beam projection, beam quality (kV and filtration), image size and patient size.